Marine-Lenhart Syndrome: Case Report, Diagnosis, and Management

MARINE LENHART SYNDROME WITH THYROID ISTHMUS AGENESIA. A NEW SYNDROME?

Thyroid isthmus agenesia (TIA) which is characterized by the absence of isthmus is one of these anomalies and its etiology is unclear. Marine Lenhart Syndrome (MLS), on the other hand, is defined as the coexistence of Graves disease and hyperactive nodules,although the diagnostic criteria are not clearly defined. Fifty five years old male patient with no concomitant disease had been diagnosed with MLS and accompanying subclinical hyperthyroidy for two years. He had dysphagia for a year. Neck ultrasound revealead retrosternal goiter with multiple hypoechoic nodules with the largest size of 33x30 mm. He had normal FT3 and FT4 levels with a decreased level of TSH. Scintigraphy revealed diffuse thyroid uptake with a hyperactive nodule of 16x11 mm on right upper lobe. Due to compressive sypmtoms and MLS he underwent surgery and diagnosed with thyroid isthmus agenesia peroperatively. MLS and TIA are rare thyroid pathologies and their etiopathogenesis has not been clarified yet. This case is thought to be the first case in which MLS and TIA coexistence was reported. Even though it is a rare disorder,having a basic knowledge about TIA can be an important step in establishing a treatment plan and avoiding possible complications. Especially in management of MLS, when surgery is considered the physician should be careful for presence of a TIA.

Type 2 Marine-Lenhart Syndrome: An Uncommon Cause of Thyrotoxicosis

Marine-Lenhart syndrome (MLS) is an uncommon cause of primary hyperthyroidism, which can occur in the context of diffuse goiter due to Graves disease (GD) or autonomic nodular disease (Plummer disease (PD)). The coexistence of these two conditions is the hallmark of the MLS. Patients with MLS have a lower remission rate with oral antithyroid drugs, requiring definitive management therapies with radioactive iodine or surgery. We present the case of a 48-year-old female with a history of primary autoimmune hyperthyroidism (GD) since 2016, with biochemical control of hyperthyroidism with methimazole but without the possibility of stopping treatment. The scintigraphic uptake pattern showed heterogeneous uptake of the thyroid parenchyma with three hyper-uptake nodules without inhibition of the rest of the thyroid tissue, findings of an MLS condition with the indication for definitive therapy, for which he was referred to nuclear medicine for the administration of radioactive iodine.

Prevalence and Treatment Outcomes of Marine-Lenhart Syndrome in Japan

INTRODUCTION

Marine-Lenhart syndrome (MLS) is now understood to be a combination of Graves' disease and autonomously functioning thyroid nodule(s) (AFTNs). The prevalence of the syndrome and suitable treatments for those living in iodine-sufficient areas are uncertain.

OBJECTIVES

We aimed to investigate the prevalence, treatment, and prognosis of MLS in Japan, an iodine-sufficient area.

METHODS

This study involved patients who visited our hospital between February 2005 and August 2019. Among patients with both thyrotoxicosis and thyroid nodule(s) larger than 10 mm, MLS and isolated AFTNs were diagnosed based on serum thyroid-stimulating hormone receptor antibody levels and scintigraphy using radioiodine or technetium-99m and thyroid uptake.

RESULTS

Twenty-two patients were found to have MLS, compared to 372 with isolated AFTNs and 8,343 with Graves' disease, during the period. Therefore, the rate of MLS cases was 0.26% among all patients with Graves' disease (22/8,343). Treatments and outcomes were assessed for cases of MLS (n = 18) and isolated AFTNs (n = 269). Antithyroid drugs (ATDs) were withdrawn in 27.8% of cases in the MLS group and 10.3% in the isolated AFTN group. There was no significant difference in the clinical outcome after ATD withdrawal between the 2 groups. However, the rate of hypothyroidism after radioactive iodine (RAI) administration was significantly higher in the MLS group than in the isolated AFTN group (42.9 vs. 9.0%, p = 0.005) despite similar doses of RAI.

CONCLUSIONS

The prevalence of MLS among patients with Graves' disease was 0.26% in Japan. RAI therapy induces hypothyroidism more frequently than in those with AFTNs probably because RAI is taken up in the surrounding Graves' tissues.

Onset of Marine-Lenhart syndrome and Graves' ophthalmopathy in a female patient treated with alemtuzumab for multiple sclerosis

BACKGROUND

Immune checkpoint blockade therapy may lead to thyroid dysfunction in 3-7% of treated patients. Alemtuzumab is a CD52 inhibitor leading to thyroid dysfunction in approximately 40% of patients. A female patient was affected by multiple sclerosis (MS) and subclinical hyperthyroidism due to an autonomously functioning thyroid nodule (AFTN). After alemtuzumab treatment, she developed aggressive clinical hyperthyroidism consistent with Marine-Lenhart syndrome.

CASE PRESENTATION

A 36-year-old woman presented in July 2019 with symptoms of hyperthyroidism and eye complaints. Three years earlier, she was diagnosed with MS. Subclinical hyperthyroidism was diagnosed in April 2017. Thyroid scintigraphy showed an intranodular distribution of ^99mTc-pertechnatate consisting of an AFTN in the right lobe of the thyroid. In June 2018, because of the MS, she was treated with alemtuzumab. In November 2018, she was started on methimazole treatment because of the symptoms of hyperthyroidism. In December 2018, thyroid function was normal under methimazole treatment. In June 2019, the patient received a second round of alemtuzumab administration. One month later, she developed symptoms of hyperthyroidism. These symptoms were accompanied by diplopia. Blood tests showed severe hyperthyroidism. Thyroid scintigraphy showed a diffuse distribution of ^99mTc-pertechnatate and the presence of a "cool" area in the right lobe of the thyroid, confirmed by ultrasonography. The nodule was diagnosed as a low-risk indeterminate lesion.

CONCLUSION

We present a case of Graves' disease with active, moderate-to-severe Graves' ophthalmopathy in a patient with pre-existing AFTN presenting with a coexisting, rare case of Marine-Lenhart syndrome associated with immune reconstitution after alemtuzumab treatment.